In recent years, the ink-jet recording method has been applied to various printing fields such as photography, various kinds of printings, and special printings such as marking and color filters because the ink-jet recording method can produce an image simply and at lower cost and more easily compared with a gravure printing method. Particularly, in the field of ink-jet recording method, an image quality almost equal to a silver halide photograph can be obtained by the following means: a recording device which enables to jet and to control a fine dot; an ink having improved properties of color reproduction area, durability, and jetting property; and an exclusive paper in which the absorptivity of the ink, coloring property of the coloring material, and surface glossiness are greatly increased.
Generally there are the following modes in an ink-jet recording device. One of them is a single pass mode which performs image recording by carrying out discharge of the ink on a recording medium from the line head having a plurality of nozzles. The line head is located in substantially orthogonal scanning direction to the conveying direction of the recording medium. The other is a scanning mode which performs image recording by a moving recording head carried in the carriage to a scanning direction, and carrying out discharge of the ink from the nozzles of the recording head during a transfer of the recording head.
Although the scanning method is the way which is used especially widely in a home ink-jet recording device, which makes a picture by allowing a head to go and come back several times, its printing speed is generally very low and as a result its manufacturing efficiency is low. Then, in the field of an industrial field, the single pass mode which is excellent in manufacturing efficiency at high speed has attracted attention recently.
However, although a single pass mode is a mode to print by one scanning (relative displacement of a head with respect to a recording medium) as mentioned above, and it can print at high speed and it is excelled in manufacturing efficiency, the jetted ink from the nozzle may produce unevenness by the effect of conveyance and the accuracy of the nozzle, which will influence the image quality to a large extent.
Moreover, multicolor printing which is more colorful and of high image quality is being required from an expanded market, although the monochrome printing of etiquette, for example, has been produced with a single pass mode printing using one color.
However, when a single pass mode ink-jet recording is employed to perform multicolor printing, after ejection of the ink, the subsequent fixation or solidification of the ejected ink may not be completed, as a result, it was found out that “bleeding” will occur which is produced by mixing inks having different colors. That is, in order to perform multicolor printing with a single pass mode ink-jet recording, it is required to figure out to control the opposite properties to produce an image of high definition. One of the opposite properties is to expand the ink droplet for suppressing the development of an uneven density, and the other is to control the bleeding without extending the ink droplet too much to reduce the uneven density.
As prior art, there is disclosed a technology in Patent document 1. In order to suppress aggregation of the ink which is one cause of generating an uneven density, this technology devised to specify a certain relationship between the resolution of the print produced with a single pass mode printing, the dot size and the diffusion coefficient of a dot at the time of colliding with the receiving layer media which carry out ink absorption so as to avoid aggregation of the inks. However, by using this technology, an uneven density was generated with substantially non-absorbing recording medium, and when this technology was used for multicolor printing, a large amount of bleeding was generated and it was not helpful.
An ink-jet recording device can be classified according to the type of ink as follows. They are: a phase change ink-jet system using a wax ink which is solid at room temperature; a solvent ink-jet system using an ink which is mainly made of a quick-drying organic solvent; and a UV curing ink-jet system using a UV curable ink hardened by irradiation with a UV light.
Among these, a UV curing ink-jet system attracts attention at a point that it is recordable on the recording medium which does not have quick drying and ink absorbency besides an exclusive printing paper, and it begins to be widely used for a single pass mode.
In patent document 2, there is disclosed a line mode ink-jet technology equipped with an active energy ray curable ink and a semi-curing light source which emits an active energy ray by making use of these advantages. According to this technology, it is describes as follow. The surface of the ink droplet which reached the target previously on the recording medium is half-cured with an activity energy ray. Then, this technology tried to reduce the fault of an uneven density by adjusting dot size and the pitch between dots so that the radius of droplets to overlap after making the ink droplet of the same color to reach the target. When a single pass mode of multicolor printing at high speed was combined with this technology, the bleeding between each ink printed in order could not be stopped, and it was a problem. Moreover, with this technology, the uneven density in the overlapping portion was also observed, and this technology did not bear practical use.
On the other hand, there is another technology in patent document 3. In this technique, when ejecting an ink hardened by irradiation with an active energy ray on a recording medium, it was newly added a manufacturing process in an under coat liquid given on the recording medium beforehand, and semi-curing of the ink is performed after this process. However, by this method, since the manufacturing process of newly applying under coat liquid is required, it is inferior to manufacturing efficiency. Moreover, although this under coat liquid and a variety of curable inks are used in an actual field, when affinity with inks was bad, chemical reactions, such as aggregation, were also generated and there was a case where the formula change of the under coat liquid was required, and not all bleeding was controlled well, and actual use including the manufacturing efficiency in the field was not able to be achieved.